I seem to recall being told that the MW has a shorter control collar length than the M pumps and as such it increases its fuel delivery quantity/mm of rack travel more quickly. This was supposedly one of the reasons for building M pumps rather than MW's as the MW's with big plungers became very touchy when on the engine. I know my M pump has a fair bit more travel on the speed control lever than my MW and that helps to reduce the sensitivity as well. Has anyone verified what the control distances are on the two pumps?